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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 661 · 40 questions
TalentJR

The trick (Pairs): Pair the first and last numbers: each pair adds to n + 1. Count the pairs — or multiply n × (n + 1) and halve it. Odd numbers 1 + 3 + 5 + …: count them and multiply that count by itself.

NameDateTime takenScore ___ / 40
  1. 1.1 + 3 + 5 + … + 49 =
  2. 2.1 + 3 + 5 + … + 19 =
  3. 3.1 + 3 + 5 + … + 33 =
  4. 4.1 + 2 + 3 + … + 56 =
  5. 5.1 + 2 + 3 + … + 42 =
  6. 6.1 + 2 + 3 + … + 73 =
  7. 7.1 + 2 + 3 + … + 64 =
  8. 8.1 + 2 + 3 + … + 69 =
  9. 9.1 + 3 + 5 + … + 15 =
  10. 10.1 + 2 + 3 + … + 61 =
  11. 11.1 + 2 + 3 + … + 6 =
  12. 12.1 + 2 + 3 + … + 71 =
  13. 13.1 + 2 + 3 + … + 50 =
  14. 14.1 + 3 + 5 + … + 41 =
  15. 15.1 + 2 + 3 + … + 90 =
  16. 16.1 + 2 + 3 + … + 15 =
  17. 17.1 + 2 + 3 + … + 80 =
  18. 18.1 + 3 + 5 + … + 13 =
  19. 19.1 + 2 + 3 + … + 10 =
  20. 20.1 + 3 + 5 + … + 29 =
  21. 21.1 + 2 + 3 + … + 44 =
  22. 22.1 + 3 + 5 + … + 25 =
  23. 23.1 + 2 + 3 + … + 98 =
  24. 24.1 + 2 + 3 + … + 9 =
  25. 25.1 + 2 + 3 + … + 23 =
  26. 26.1 + 2 + 3 + … + 30 =
  27. 27.1 + 2 + 3 + … + 74 =
  28. 28.1 + 3 + 5 + … + 39 =
  29. 29.1 + 2 + 3 + … + 19 =
  30. 30.1 + 3 + 5 + … + 43 =
  31. 31.1 + 3 + 5 + … + 45 =
  32. 32.1 + 3 + 5 + … + 17 =
  33. 33.1 + 2 + 3 + … + 28 =
  34. 34.1 + 2 + 3 + … + 27 =
  35. 35.1 + 2 + 3 + … + 57 =
  36. 36.1 + 3 + 5 + … + 23 =
  37. 37.1 + 2 + 3 + … + 60 =
  38. 38.1 + 3 + 5 + … + 35 =
  39. 39.1 + 2 + 3 + … + 68 =
  40. 40.1 + 2 + 3 + … + 48 =

Answer key

  1. 625
  2. 100
  3. 289
  4. 1596
  5. 903
  6. 2701
  7. 2080
  8. 2415
  9. 64
  10. 1891
  11. 21
  12. 2556
  13. 1275
  14. 441
  15. 4095
  16. 120
  17. 3240
  18. 49
  19. 55
  20. 225
  21. 990
  22. 169
  23. 4851
  24. 45
  25. 276
  26. 465
  27. 2775
  28. 400
  29. 190
  30. 484
  31. 529
  32. 81
  33. 406
  34. 378
  35. 1653
  36. 144
  37. 1830
  38. 324
  39. 2346
  40. 1176

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